This invention relates to manhole/maintenance access hole installation during roadway construction and more particularly to an apparatus that attaches to a manhole cover frame, allowing the manhole cover to be adjusted until it is parallel with and in the same plane with the proposed final or final finished grade of the surfaced roadway.
When resurfacing an existing roadway or installing new roads with manholes, it is difficult to position the manhole cover frame accurately so that it is flush with the proposed finished grade of the roadway surface. Manholes are most prevalently made in precast concrete sections and a common configuration consists of a manhole base upon which standard precast manhole sections interlockingly stack. Since the manholes are not necessarily perpendicular to the roadway surfaces, these standard precast manhole sections terminate below grade. Shorter, lighter precast riser rings are interlockingly placed on the top manhole section. Grout or other suitable material is then used between these riser rings and the manhole section to adjust the top end of the riser rings parallel to the proposed grade of the roadway surface. A manhole cover frame, which is typically a large cylindrical cast iron section with internal and external flanges, is placed onto the riser rings. However, since the manhole cover frame weighs hundreds of pounds but must be precisely placed so as to be flush with the finished surface of the roadway and since the riser rings are only roughly positioned with respect to the contour and elevation of the roadway surface, the manhole cover cannot just rest directly upon the precast concrete riser rings, but must be adjusted to precise height and angle relative to the riser rings. Due to the extreme weight of the manhole cover frame, accomplishing precise alignment is difficult. Typically the cover frame is held in proper alignment by the placement of stones or other debris, which may be handy, between the manhole cover frame and the riser rings.
Referring to FIG. 1, a cross sectional view of a typical manhole cover frame 10, the frame includes an outer peripheral flange 12 that is supported directly on the top surface of a riser ring 14. The riser rings 14 have been adjusted to conform with the roadway grade 18 by the strategic placement of a grout 16 between riser rings 14.
An alternate method of alignment is to suspend the manhole cover frame by wire from dimensional lumber that rests on the finished grade of the roadway.
Prior patents for manhole leveling devices also disclose several methods for aligning the manhole frame to the finished roadway surface. U.S. Pat. No. 1,076,386 discloses using leveling screws but requires special fabrication of the cover frame to incorporate brackets to house and support the screws. U.S. Pat. No. 4,075,796 shows a specially fabricated cover frame with an internally threaded body that adjusts for height only. U.S. Pat. No. 3,263,579 also discloses using leveling screws but requires a specially fabricated flange from which the leveling screws operate. U.S. Pat. No. 2,930,295 uses screws to align the manhole cover but requires the fabrication of a two-piece cover frame.
The present invention provides a cost effective apparatus and method for precise alignment of a manhole cover frame to a proposed roadway surface that requires no modifications to existing manhole components, nor requires any additional steps in the manufacture of existing manhole components.
This invention comprises a clip that fastens to the outer peripheral flange on a manhole cover frame. The clip is threaded to allow a leveling bolt to raise or lower the manhole cover frame with respect to the topmost manhole precast riser ring, allowing for the perfect alignment of the manhole cover frame with the roadway surface. The individual clips may be positioned anywhere along the peripheral flange of the cover frame in accordance with the contour of the roadway surface.
Accordingly, it is an object of the present invention to provide an improved low cost manhole cover frame leveling apparatus.
It is a further object of the present invention to provide an improved manhole cover frame leveling apparatus that requires no modifications to existing manhole components.
It is yet another object of the present invention to provide an improved manhole cover frame leveling apparatus that requires minimal time, effort and equipment to install and to use.
It is yet another object of the present invention to provide an improved leveling clip that is suitable for performing a variety of construction leveling tasks with respect to installation of gratings, covers and the like.
The subject matter of the present invention is particularly pointed out and distinctly claimed in the concluding portion of this specification. However, both the organization and method of operation, together with further advantages and objects thereof, may best be understood by reference to the following description taken in connection with accompanying drawings wherein like reference characters refer to like elements.